采用DWR的话，效果真是立竿见影，虽然说可能破坏MVC设计模式这一思想，但是他那低耦合的程序调计方法，就好像在用开发CS程序一样简单。以前用ajax写程序时，时间花的最多的也就是JS部分，现在有了DWR以后，我可以不用再调试复杂的js，把精力集中在业务逻辑上，这样必将事半功倍！刚刚学了一个入门级的实例，为了供大家学习，我把源码贴出来！不要见笑，我也是初学DWR。
首先配置web.xml,代码如下：
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<display-name>sjf</display-name>
<description>sjf</description>
<servlet>
<servlet-name>dwr-invoker</servlet-name>
<display-name>DWR Servlet</display-name>
<description>Direct Web Remoter Servlet</description>
<servlet-class>uk.ltd.getahead.dwr.DWRServlet</servlet-class>
<init-param>
<param-name>debug</param-name>
<param-value>true</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>dwr-invoker</servlet-name>
<url-pattern>/dwr/*</url-pattern>
</servlet-mapping>
</web-app>
dwr.xml文件配置：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 1.0//EN" "http://www.getahead.ltd.uk/dwr/dwr10.dtd">
<dwr>
<!-- without allow, DWR isn't allowed to do anything -->
<allow>
<create scope="application" creator="new" javascript="checkLogin">
<param name="class" value="com.test.ajax.UserLogin"/>
</create>
</allow>
</dwr>
Java文件(UserLogin.java)代码:
package com.test.ajax;
public class UserLogin{
private String usern;
private String passwd;
public UserLogin(){
}
public String checkLogin(){
if(usern.equals("admin") && passwd.equals("admin")){
return "login success!";
}else{
return "login faild!";
}
}
public void setField(String usern,String passwd){
this.usern=usern;
this.passwd=passwd;
}
public static void main(String args[]){
UserLogin ul=new UserLogin();
ul.setField("admin","admin");
System.out.println(ul.checkLogin());
}
}
jsp文件（当然完全可以用html文件替代）代码如下:
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>dwr for user login</title>
<script type="text/javascript" src="<%=request.getContextPath()%>/dwr/interface/checkLogin.js"></script>
<script type="text/javascript" src="<%=request.getContextPath()%>/dwr/engine.js"></script>
<script type="text/javascript" src="<%=request.getContextPath()%>/dwr/util.js"></script>
<script language="javascript">
var mycall=function callBack(data){
alert(data);
}
function login(){
var un=document.getElementByIdx("form_usern");
var pd=document.getElementByIdx("form_passwd")
checkLogin.setField(un.value,pd.value);
checkLogin.checkLogin(mycall);
}
</script>
</head>
<body>
<h1>User login</h1>
<label for="form_usern">用户：</label><input type="text" id="form_usern"/><br/>
<label for="form_passwd">密码：</label><input type="password" id="form_passwd"><br/>
<input type="button" value="登录" onclick="javascript:login()">
</body>
</html>
注：请确保在\WEB-INF\lib文件夹下有dwr.jar文件的存在